Dr Raul Gimenez1, Dr Esteban Jobbagy3, Wilson Schultz, MSc Jorge Luis Mercau4
1SARDI. South Australian Research & Development Institute, 2University of Tasmania, 3CONICET. National Research Council of Argentina, 4INTA. National Institute of Agricultural Technology
Biography:
Agronomist, MSc and PhD from University of Buenos Aires, Argentina. Researcher at CONICET (National Research Council of Argentina).Visiting researcher at South Australian Research & Development Institute (SARDI) and PhD candidate at University of Tasmania.Post-doc fellow at University of Queensland
Abstract:
Dryland salinity, a well-known challenge in Australia, is emerging as a novel threat in the South American Dry Chaco. Large-scale deforestation of native dry forests for agriculture has caused rising groundwater tables, jeopardizing crops with flooding and salinization. This collaborative study between farmers and researchers explores the role of different rotation components in managing shallow water tables in this region with summer-dominated rainfall, where soybean and maize are the main cash crops. Our findings reveal that chemical fallows maintained shallow water tables (above 1 meter), increasing the risk of waterlogging for summer crops. Rye cover crops before soybean initially deepened water tables to 2.2 meters before spraying, but increased infiltration and groundwater recharge afterwards, having limited impact on the end. Wheat in double-cropping systems, had a higher water use during winter-spring that lowered water tables down to 3 meters. Early-sown hairy vetch cover crops proved the most effective strategy to lower water tables in wet years, reaching >5 m depths, but representing a significant hydric cost for following crops in dry years. Early-sown summer cash crops had higher water use than those sown later early in the season, contributing to lower water tables and to increase system resilience to intense rainfall events. Beyond these results, this research underscores the value of farmer-researcher collaborations in developing sustainable agricultural practices to address emerging environmental challenges like dryland salinity in the Dry Chaco.